Emergency department visits involving cannabis hyperemesis syndrome rose sharply across the United States after October 2025, according to a new CDC surveillance report, and the report's own authors identify the most likely reason: clinicians finally got a diagnosis code for it.
The analysis, published in the Morbidity and Mortality Weekly Report on August 6, examined national syndromic surveillance data from January 2023 through May 2026 and identified 199,565 emergency visits involving the condition among more than 407 million all-cause visits.
The jump was abrupt. In September 2025, before the code took effect, 3.35 of every 10,000 emergency visits involved cannabis hyperemesis syndrome. In October 2025, the first month the code was available, that figure reached 11.26 per 10,000.
A Measurement Change Sits at the Center of the Numbers
Before October 2025, cannabis hyperemesis syndrome had no dedicated code in the International Classification of Diseases. Clinicians identified it indirectly by combining a cyclical vomiting or nonspecific emesis code with a cannabis-related diagnosis code, an approach that missed cases and could be confused with other gastrointestinal conditions.
On October 1, 2025, a specific code took effect. Across the first eight months of its use, the average monthly proportion of these visits was 11.97 per 10,000, which is 3.7 times the monthly average of 3.19 recorded from January 2023 through September 2025. During that earlier period, the proportion had remained mostly steady, including across demographic subgroups.
The report's authors wrote that the abruptness and sustained magnitude of the increase likely reflects, at least in part, improved clinical recognition and coding "rather than a true and immediate rise in incidence."
That is an unusually clear statement for a surveillance report, and it should shape how readers interpret the finding. The most defensible conclusion is that the condition was previously undercounted, not that a wave of new illness appeared in a single month. Some coverage has described the change as a surge in cases. The data as published describe a surge in identified cases. The authors add that the postcode figures may be the more accurate picture of the condition's real burden in emergency care.
The Condition Is Real, Distinctive and Frequently Missed
Cannabis hyperemesis syndrome is characterized by cyclical episodes of severe nausea, vomiting and abdominal pain associated with frequent, long-term cannabis use. It is disorienting to patients partly because cannabis is widely understood as an antiemetic.
The clinical picture typically involves recurring bouts of intractable vomiting separated by symptom-free intervals. A hallmark that clinicians look for is compulsive hot bathing or showering during episodes, which patients often discover on their own provides temporary relief. Very hot water carries a scalding risk, which is worth raising with a clinician rather than treating as a solution.
The syndrome has long been described in people with heavy use over extended periods, but the CDC report notes emerging evidence that symptom onset can begin sooner than previously estimated, in some cases within the first year of use. Studies have also reported delays of several years between symptom onset and diagnosis.
Distinguishing this from other causes of cyclic vomiting is the hard part, and it is why the condition is often missed. Cyclic vomiting syndrome unrelated to cannabis, gastroparesis, gallbladder disease, bowel obstruction, and pregnancy-related hyperemesis can all present with repeated vomiting. The evaluation frequently involves imaging and laboratory work to exclude those causes, which is expensive and, when the diagnosis is delayed, sometimes repeated across multiple visits.
Repeated vomiting also has genuine medical consequences, including dehydration, electrolyte disturbance, and kidney injury, which is why some patients require intravenous fluids and admission. Outcomes range from full resolution after cessation to, rarely, death.
Young Adults and Women Appear Disproportionately in the Data
CDC reported higher proportions of these emergency visits among people aged 15 to 24 and among females, with differences by race and ethnicity also emerging after the code took effect. Among people aged 15 to 24, the average monthly proportion after implementation was 38.70 per 10,000 visits, well above the figure for any older age group.
That age concentration is consistent with what clinicians have described in states with legal retail cannabis, where high-potency flower and concentrates are widely available. The report notes that THC concentrations in cannabis products have risen over time and that higher-potency products are associated with more frequent use, the primary risk factor for the syndrome. Potency itself has not been directly linked to the condition, and the surveillance data describe emergency visits and demographics rather than product type, frequency or duration of use.
The people most affected are frequent, long-term cannabis users, particularly younger adults. Occasional users are not the population described in this report. Households with a young adult who has had repeated unexplained vomiting episodes and multiple emergency visits without a diagnosis may find this report clinically relevant, since a specific diagnosis can end a cycle of repeated testing.
The only approach that resolves the syndrome is stopping cannabis use, with symptoms typically improving over days to weeks after cessation, though relapse with resumed use is common. Anyone considering stopping should discuss it with a clinician, particularly if cannabis is being used for a medical indication. Support for cannabis use disorder is available through SAMHSA's national helpline at 1-800-662-4357, which is free and confidential.
Surveillance Continues, and Better Data Are Coming
The most useful consequence of the new code is that it makes future trends interpretable. Once several years of consistently coded data accumulate, researchers will be able to distinguish real changes in incidence from the artifact of a measurement shift, which is not possible today.
The report's authors called for strengthening education about risks associated with frequent cannabis use, expanding surveillance, and improving clinical recognition through continuing medical education and routine assessment of cannabis use in emergency settings. They also pointed communities toward CDC's evidence-based prevention resources for youth substance use.
Several things remain unknown. The report does not establish whether true incidence is rising, does not link visits to product potency or purchase source, and does not measure how many patients were correctly diagnosed at their first visit. Whether emergency departments adopt the new code uniformly across states is also unresolved, and the data cover only patients sick enough to seek emergency care, drawn from about 70 percent of facilities in the national surveillance program that reported consistently.
The confirmed fact is that identified emergency visits rose 3.7 times after a specific diagnosis code became available, against a previously steady baseline. The people most affected are frequent long-term cannabis users, especially those aged 15 to 24. The most reasonable action for someone with recurring severe vomiting is a clinical evaluation that includes an honest account of cannabis use, since that history changes the differential diagnosis. The central uncertainty is how much of the increase reflects better detection versus real change. MedicalDaily will report on subsequent CDC surveillance updates.
Key Questions Answered
What did the CDC report find? Emergency visits involving cannabis hyperemesis syndrome rose from 3.35 per 10,000 visits in September 2025 to 11.26 per 10,000 in October 2025, and averaged 3.7 times the prior monthly baseline over the following eight months. Nearly 200,000 such visits were identified from January 2023 through May 2026.
Does this mean more people are getting sick? Not necessarily. The report's authors state the increase likely reflects improved clinical recognition and coding rather than a true and immediate rise in incidence, following the introduction of a dedicated diagnosis code.
What is cannabis hyperemesis syndrome? It is a condition marked by cyclical episodes of severe nausea, vomiting and abdominal pain associated with frequent, long-term cannabis use, often with symptom-free intervals between episodes.
How is it distinguished from other causes of vomiting? Clinicians must rule out cyclic vomiting syndrome unrelated to cannabis, gastroparesis, gallbladder disease, obstruction and pregnancy-related causes. A pattern of compulsive hot bathing for relief is a recognized clue.
Who is most affected? The data show higher proportions among people aged 15 to 24 and among females. The condition is associated with frequent, long-term use rather than occasional use.
What is the treatment? Stopping cannabis use is the only approach that resolves the syndrome, with symptoms typically improving over days to weeks. Emergency treatment addresses dehydration and electrolyte problems. Decisions about stopping should involve a clinician.
When should someone go to an emergency department? Persistent vomiting with inability to keep fluids down, signs of dehydration, severe abdominal pain, confusion or reduced urination warrant urgent evaluation.
